Nearing the First Standard for Energy Storage Systems

Production of renewable energy from the sun and wind has grown dramatically. With it, interest has also risen sharply for grid-scale energy storage systems that could help store power when there’s less demand. Storage allows the power to be used later, when energy demand is high and supply is limited, or when the wind isn’t blowing or the sun isn’t shining.

But widespread adoption of energy storage technologies has been partially hampered by the lack of a uniform method to compare and contrast the numerous storage systems that are currently being sold. Now, a group of industry stakeholders and government representatives have developed a way to effectively compare energy storage system performance. The working group, organized through the Energy Storage Systems Program within the Department of Energy’s Office of Electricity Delivery and Energy Reliability, has developed the first-ever protocol to evaluate energy storage system performance.

“Without this protocol, comparing the ability of two different systems to handle the same situation was like comparing apples to oranges,” said Pacific Northwest National Laboratory engineer David Conover, who oversaw the protocol effort for DOE. “Now energy storage systems can be evaluated on a reliable, level playing field.”

PNNL and another DOE lab, Sandia National Laboratories, helped organize the working group in February 2012 on behalf of DOE. The working group consisted of more than 100 participants who responded to an open invite. The group’s members represented more than 60 different organizations, including storage technology developers, utilities, professional societies, academia, government institutions and other interested parties.

Getting a standard fully developed and approved usually takes several years. As an informal body, the working group was able to draft the protocol in less than a year, which should help jump start the more formal standard development process. In the meantime, a uniform set of criteria has been established that can be used now. The working group moved quickly because of the immediate and growing need for energy storage performance standards.

“Using the protocol now and having a formal standard later will enable utilities to more accurately weigh the costs and benefits of installing energy storage systems and justify the expense to ratepayers and investors,” Conover said.

The protocol addresses how energy storage systems perform in two areas: peak shaving and frequency regulation. Peak shaving involves storing energy on a system when abundant, cheap power is available on the electric grid, and discharging stored energy for use when there’s high demand and power is expensive. Peak shaving also involves storing renewable energy until weather conditions, such as a lull in wind or cloudy skies, prevent more power from being generated. Frequency regulation helps maintain the power grid’s frequency at a constant 60 Hertz, and requires frequent energy storage to balance power generation and demand. While peak shaving can happen over the course of several hours, frequency regulation has to happen very quickly, as often as every three to five seconds.

Recognizing there are more than just two uses for energy storage systems, the working group is reconvening in 2013 to expand the protocol to other uses. PNNL and Sandia would like to expand the working group’s membership so that more professionals who might use or benefit from the protocol can contribute.

A new users’ group is also being established to apply peak shaving and frequency regulation to energy storage systems in real-world situations. The users’ group will help provide important information that is needed to fine-tune the current protocol and further inform the standard development process. Those interested in participating in either group can email Kathy Bray of PNNL at kathy.bray@pnnl.gov.